Optical film and display assembly applying the same

ABSTRACT

An optical film and a display assembly applying the optical film are provided. The optical film may comprise a plurality of truncated tapered units embedded in a material layer for transmitting a light emitted from the display unit by reflecting the light through a reflection surface between the truncated tapered units and the material layer, wherein a ratio of the area of a first end surface where the light emerges from each truncated tapered unit and the area of a second end surface where the light is incident into each truncated tapered may be between 0.2 and 0.6. Furthermore, a light absorbing layer may be formed on a light output side of the optical film for absorbing ambient light.

TECHNICAL FIELD

The technical field relates to an optical film and a display assemblyapplying the same.

BACKGROUND

The current generation is frequently proclaimed as the 3C era: theComputer, the Communication and the Consumer electronics era. In ourdaily life, we encounter many kinds of information products such asmobile phones, personal digital assistants (PDAs), global positioningsatellite (GPS) systems and digital cameras. Most information equipmentuses a flat panel display as the main communication medium. For example,liquid crystal displays, plasma displays and organic light emittingdiode (OLED) panels are available for selection. The OLED panel not onlyhas higher brightness level, lower power consumption, higher contrast,rapid response and lower driving voltage, but also has the capability tobe miniaturized according to the current trend of communicationequipment. Therefore, a large number of OLED panel products aredeveloped in recent years.

In the case of OLED panel, a metallic electrode is used to enhance lightextraction efficiency. However, in an environment with high ambientbrightness, ambient light may enter the OLED panel and is reflected bythe metallic electrode with high reflectivity, which reduces visualcontrast of the display panel and affects the image quality.

SUMMARY

According to an embodiment, an optical film comprises a transparentsubstrate, a material layer, a plurality of truncated tapered units, anda light absorbing layer. The transparent substrate has a carryingsurface. The material layer is disposed on the carrying surface of thetransparent substrate. The plurality of truncated tapered units isdisposed in the material layer, and each of the truncated tapered unitshas a first end surface nearby the carrying surface and a second endsurface away from the carrying face, wherein a ratio of the area of thefirst end surface and the area of the second end surface may be largerthan or equal to 0.2 and less than or equal to 0.6. A reflection surfaceis formed between each of the truncated tapered units and the materiallayer to reflect a light which enters the truncated tapered unit throughthe second end surface, and the light reflected by the reflectionsurface is adapted to emerge from the truncated tapered unit through thefirst end surface. In addition, the light absorbing layer is disposed onthe carrying surface and located between the transparent substrate andthe material layer, wherein the light absorbing layer has a plurality ofopenings, and a vertical projection of the openings on the carryingsurface overlaps a vertical projection of the first end surfaces of theplurality of truncated tapered units on the carrying surface.

According to another embodiment, a display assembly comprises a displayunit having a display side, and an optical film disposed on the displayside of the display unit. The optical film comprises a transparentsubstrate, a material layer, a plurality of truncated tapered units, anda light absorbing layer. The transparent substrate has a carryingsurface facing the display unit. The material layer is disposed on thecarrying surface of the transparent substrate. The plurality oftruncated tapered units is disposed in the material layer, and each ofthe truncated tapered units has a first end surface nearby the carryingsurface and a second end surface away from the carrying face, wherein aratio of the area of the first end surface and the area of the secondend surface is larger than or equal to 0.2 and is less than or equal to0.6. A reflection surface is formed between each of the truncatedtapered units and the material layer to reflect a light which is emittedfrom the display unit and enters the truncated tapered unit through thesecond end surface, and the light reflected by the reflection surface isadapted to emerge from the truncated tapered unit through the first endsurface. The light absorbing layer is disposed on the carrying surfaceand located between the transparent substrate and the material layer,wherein the light absorbing layer has a plurality of openings, and avertical projection of the openings on the carrying surface overlaps avertical projection of the first end surfaces of the plurality oftruncated tapered units on the carrying surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments of thedisclosure and, together with the description, serve to explain theprinciples of the disclosure.

FIG. 1 illustrates a display assembly applying an optical film accordingto an embodiment of the present disclosure.

FIG. 2 further shows a partial enlarged view of the display assembly 10of FIG.

FIG. 3 shows a table illustrating the relationship between the lighttransmittance and the geometry of the truncated tapered unit.

FIG. 4 shows a table illustrating the relationship between the lightreflectance and the geometry of the truncated tapered unit.

FIG. 5 shows a table illustrating light extraction efficiency versus thedistance D.

FIG. 6 shows a table illustrating total reflection and effectivereflection versus the distance D.

FIG. 7A illustrates a display assembly according to another embodimentof the present disclosure.

FIG. 7B illustrates a display assembly according to another embodimentof the present disclosure.

FIG. 7C illustrates a display assembly according to another embodimentof the present disclosure.

FIG. 8 illustrates a display assembly according to another embodiment ofthe present disclosure.

FIG. 9 illustrates a display assembly according to another embodiment ofthe present disclosure.

FIG. 10 illustrates a display assembly according to another embodimentof the present disclosure.

FIG. 11 illustrates an optical film according to another embodiment ofthe present disclosure.

FIG. 12 and FIG. 13 illustrate different optical films according toother embodiments of the present disclosure.

FIG. 14 illustrates an optical film according to another embodiment ofthe present disclosure.

FIG. 15 illustrates an optical film according to another embodiment ofthe present disclosure.

FIG. 16 illustrates an optical film according to another embodiment ofthe present disclosure.

FIG. 17 illustrates a display assembly according to another embodimentof the present disclosure.

FIG. 18 illustrates a display assembly according to another embodimentof the present disclosure.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

Reference will now be made in detail to the present embodiments of thedisclosure, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

FIG. 1 illustrates a display assembly applying an optical film accordingto an embodiment of the present disclosure. The display assembly 10comprises a display unit 100 having a display side 101, and an opticalfilm 200 disposed on the display side 101 of the display unit 100.Herein, the display unit 100 may be a liquid crystal display (LCD), aplasma display, an OLED display, an electrowetting display (EWD), anelectro-phoretic display (EPD), an electrochromic display (ECD) or anyother applicable display device, which displays image or other visualinformation from the display side 101.

The optical film 200 includes a transparent substrate 210 having acarrying surface 212 facing the display unit 100, and the material ofthe transparent substrate 210 may be at least one of polyimide (PI),polycarbonate (PC), polyethersulfone (PES), polyacrylate (PA),polynorbornene (PNB), polyethylene terephthalate (PET),polyetheretherketone (PEEK), polyethylene naphthalate (PEN),polyetherimide (PEI), and glass etc.

A material layer 220 is disposed on the carrying surface 212 of thetransparent substrate 210. The material layer 220 can be made ofpolymer, resin, phtosensitive resin, positive photoresist, negativephotoresist, etc. Furthermore, a plurality of truncated tapered units230 is disposed in the material layer 220, and each of the truncatedtapered units 230 has a first end surface 232 nearby the carryingsurface 212 and a second end surface 234 away from the carrying face212. A total internal reflection surface S is foamed between each of thetruncated tapered units 230 and the material layer 220 to reflect alight L which is emitted from the display unit 100 and enters thetruncated tapered unit 230 through the second end surface 234. The lightL reflected by the total internal reflection surface S is adapted toemerge from the truncated tapered unit 230 through the first end surface232. In the present embodiment, the shape of each of the truncatedtapered units 230 may be a cylinder, an elliptic cylinder, a squarecolumn, a rectangular column, a rhombus column or irregular columns.

A light absorbing layer 240 is disposed on the carrying surface 212 andlocated between the transparent substrate 210 and the material layer220. Herein, the light absorbing layer 240 may be a black matrix, andhas a plurality of openings 242, wherein a vertical projection of theopenings 242 on the carrying surface 212 overlaps a vertical projectionof the first end surfaces 232 of the plurality of truncated taperedunits 230 on the carrying surface 212. In other words, the lightabsorbing layer 240 exposes the first end surfaces 232 of the truncatedtapered units 230 for the light L to emerge from the truncated taperedunit 230 through the first end surface 232.

Although an area of the opening 242 of the light absorbing layer 240 isequal to an area of the first end surface 232 of the truncated taperedunit 230 in FIG. 1, the disclosure of the application is not limitedthereto. In other embodiments, the area of the opening of the lightabsorbing layer may be larger than or smaller than an area of the firstend surface of the truncated tapered unit.

FIG. 2 further shows a partial enlarged view of the display assembly 10of FIG. 1. Referring to FIG. 1 and FIG. 2, the light L emitted from thedisplay unit 100 can be transmitted through the optical film 200 by thetruncated tapered units 230 to maintain high light extraction efficiencyof the display unit 100. In addition, a proportion of ambient light V1irradiated to the optical film 200 is absorbed by the light absorbinglayer 240, while other proportion of ambient light V2 incident into thetruncated tapered units 230 through their first end surfaces 232 mayreturn by the same path as shown by the dashed line. Therefore, in oneof embodiments, being emitted to the optical film 200, only a littleproportion of ambient light will be transmitted to the eyes of a user.High visual contrast can be obtained even if the display assembly 10 isplaced in an environment with high ambient brightness.

In the present embodiment, the geometry of the truncated tapered units230 is further defined to achieve favourable light extractionefficiency. Taking a cylindrical truncated tapered unit 230 as a sample,the first end surface 232 and the second end surface 234 are circularand are respectively provided with a diameter R1 and a diameter R2, asshown in FIG. 2. The height of each of the truncated tapered unit 230 isH. FIG. 3 further shows a table illustrating the relationship betweenthe light transmittance and the geometry of the truncated tapered unit.FIG. 4 further shows a table illustrating the relationship between thelight reflectance and the geometry of the truncated tapered unit. In thesimulation of FIG. 3 and FIG. 4, the height H of the truncated taperedunit 230 is about 20 μm. The X-coordinate refers to the diameter R2, andthe Y-coordinate refers to a value r defined as a ratio between an areaof the first end surface 232 and an area of the second end surface 234.In practical use, high transmittance is desirable to improve lightextraction efficiency, while lower reflectance helps to reducereflection of ambient light. According to FIG. 3 and FIG. 4, it can beseen that the transmittance may go higher than 40% when r is greaterthan 0.2, and the reflectance get lower than 18% when r is less than0.6. Therefore, r may be considered to range from 0.2 to 0.6, and may befurther limited from 0.25 to 0.5, or even from 0.35 to 0.45, to meetvarious practical requirements.

The distance between the optical film 200 and the display unit 100 is D.FIG. 5 shows a table illustrating light extraction efficiency versus thedistance D. FIG. 6 shows a table illustrating total reflection andeffective reflection versus the distance D. Herein, “total reflection”means sum of reflection of lights in various angles, and “effectivereflection” means reflection of lights entering an eye of a user. Asshown in FIG. 5 and FIG. 6, when D is greater than 250 μm, the lightextraction efficiency goes down, while the total reflection and theeffective reflection are kept almost unchanged. Thus, D may beconsidered to be less than or equal to 250 μm. For example, D may beless than or equal to 100 μm, or less than or equal to 50 μm.

Referring to FIG. 1 again, in this embodiment, the truncated taperedunits 230 can be made of photoresist material, such as polymer, resin,photosensitive resin, positive photoresist, negative photoresist, etc.,which has a refractive index ranged from 1.3 to 1.9. The material layer220 as mentioned above has a refractive index ranged from 1.0 to 1.8.The refractive index of each of the truncated tapered units 230 ishigher than the refractive index of the material layer 220, and thereby,the total internal reflection surface S can be formed on the interfacebetween each of the truncated tapered units 230 and the material layer220.

Furthermore, in the case of the display unit 100 comprising a pluralityof pixels P, an area of each pixel P is considered to be greater thanthe area R2 of the second end surface 234 of each of the truncatedtapered units 230, such that the accurate alignment process inassembling the display unit 100 and the optical film 200 can be omitted.However, in other embodiments of the disclosure, the area of the secondend surface 234 may further be equal to the area of each pixel P, toachieve higher light utilization efficiency.

The structure of the optical film or the display assembly with the totalinternal reflection surface S is not limited to that mentioned in theabove embodiment. Display assemblies or optical films of otherembodiments are described below with reference of FIG. 7A to FIG. 18. Inthe following descriptions, differences of the embodiments are mainlydescribed, and the parts with the same technical contents are notrepeated.

FIG. 7A illustrates a display assembly according to another embodimentof the present disclosure. In this embodiment, the optical film 700further comprises a lining layer 750 interlaid between each of thetruncated tapered units 730 and the material layer 720. The lining layer750 can be made of single or multiple dielectric material layerscomprising such as silicon oxide (SiOx), silicon nitride (SiNx), indiumtin oxide (ITO), zinc oxide (ZnO), etc., which has a refractive indexranged from 1.7 to 2.5. The material layer 720 can be made ofphotoresist, which has a refractive index ranged from 1.3 to 1.7. Therefractive index of the lining layer 750 is higher than the refractiveindex of the material layer 720, and thereby, the total internalreflection surface S can be formed on the interface between the lininglayer 750 and the material layer 720. Due to the existence of the lininglayer 750, material selection of the truncated tapered units 730 is moreflexible and can be the material having refractive index higher, loweror even equal to that of the material layer 720.

FIG. 7B illustrates a display assembly according to another embodimentof the present disclosure. In this embodiment, the optical film 702 issimilar to the optical film 700 of FIG. 7A, except that the material ofthe lining layer 752 interlaid between each of the truncated taperedunits 730 and the material layer 720 is metal, such as aluminium (Al),chrome (Cr), molybdenum (Mo), silver (Ag), or alloy of theaforementioned metal. The lining layer 752 is capable of reflectinglight and thereby a reflection surface S is formed on the interfacebetween the lining layer 750 and each of the truncated tapered units730.

In the previous embodiment, the lining layer 752 is located at the sidewall of each of the truncated tapered units 730. However, in furtherother embodiments, the location of the lining layer may be variedaccording to practical requirement. FIG. 7C illustrates a displayassembly according to another embodiment of the present disclosure.

In this embodiment, the optical film 704 is similar to the optical film702 of FIG. 7B, except that the lining layer 754 is not only interlaidbetween each of the truncated tapered units 730 and the material layer720, but also covering the bottom surface of the material layer 720.Thereby, part of the light emitted from the display unit 100 toward thematerial layer 720 can be reflected by the lining layer 754 on thebottom surface of the material layer 720, and thus more light can enterthe truncated tapered units 730, so as to improve the light extractionefficiency.

FIG. 8 illustrates a display assembly 800 according to anotherembodiment of the present disclosure. In this embodiment, the lininglayer 850 not only interlaid between each of the truncated tapered units830 and the material layer 820, but also covers the first end surface832 of each of the truncated tapered units 830 and the second surface824 of the material layer 820. The lining layer 850 can be made ofsingle or multiple dielectric material layers comprising such as siliconoxide (SiOx), silicon nitride (SiNx), indium tin oxide (ITO), zinc oxide(ZnO), etc, which has a refractive index ranged from 1.7 to 2.5. Thetruncated tapered units 830 may be formed by applicable resin materialshaving a refractive index lower than 1.7 (e.g., from 1.3 to 1.7). Andthe lining layer 850 may be formed after forming the truncated taperedunits 830. The total internal reflection surface S can be formed on theinterface between the lining layer 850 and the material layer 820.

FIG. 9 illustrates a display assembly according to another embodiment ofthe present disclosure. In this embodiment, the material for forming thematerial layer 920 does not fill the gaps between the truncated taperedunits 930 when fabricating the optical film 900. In detail, the materiallayer 920 includes and air gaps 924 between the truncated tapered units930 and body portion 922. It is know that the refraction index of air isabout 1, and the material of the truncated tapered units 930 (such asphotoresist) generally has a higher refraction index, such that thetotal internal reflection surface S can be formed on the interfacebetween the truncated tapered units 930 and the air gaps 924.

FIG. 10 illustrates a display assembly according to another embodimentof the present disclosure. In this embodiment, a reflective layer 1050is formed between the light absorbing layer 1040 and the material layer1020. During the fabrication of the optical film 1000, the reflectivelayer 1050 and the light absorbing layer 1040 can be patterned with thesame mask by conducting only one exposure process to both of thereflective layer 1050 and the light absorbing layer 1040. Alternatively,the reflective layer 1050 and the light absorbing layer 1040 can bepatterned with the same mask by conducting different exposure processesto the reflective layer 1050 and the light absorbing layer 1040individually. Thus, the reflective layer 1050 and the light absorbinglayer 1040 are substantially in the same pattern. The material of thereflective layer 1050 comprises metal, such as aluminium (Al), chromium(Cr), molybdenum (Mo), silver (Ag), or alloys including the abovematerials. Some of the light L can be reflected by the reflective layer1050 and then transmitted through and emerging from the truncatedtapered units 1030, as shown by the dashed line.

FIG. 11 illustrates an optical film according to another embodiment ofthe present disclosure. In this embodiment, the optical film 1100 can befabricated over a carrier 1150, wherein the transparent substrate 1110is disposed on the carrier 1150 through a de-bonding layer 1160, andthen the light absorbing layer 1140, the material layer 1120 and thetruncated tapered units 1130 are fowled on the transparent substrate1110. The carrier 1150 may be a glass substrate or a silicon wafer. And,the carrier 1150 and the de-bonding layer 1160 may be removed afterbonding the optical film 1100 to the display unit 100 (as shown in FIG.1).

In other embodiments, the optical film may be provided with a barrierlayer for preventing gas or moisture from entering the optical film orthe display assembly. FIG. 12 and FIG. 13 illustrate different opticalfilms according to other embodiments of the present disclosure. As shownin FIG. 12, a barrier layer 1250 is formed over the carrying surface1212 of the transparent substrate 1210, and the light absorbing layer1240 is disposed on the barrier layer 1250. And, as shown in FIG. 13, abarrier layer 1350 is formed over the carrying surface 1312 of thetransparent substrate 1310 and the light absorbing layer 1340. Thebarrier layer 1250 or 1350 may comprise an organic layer, an inorganiclayer, or an at least two-layered stacked structure formed byinterlacing the organic layer and the inorganic layer.

The second end surface of each of the truncated tapered units and thesecond surface of the material layer may be coplanar as shown in theaforementioned embodiments. Otherwise, the second end surface of each ofthe truncated tapered units and the second surface of the material layermay further be non-coplanar in other embodiments. FIG. 14 illustrates anoptical film according to another embodiment of the present disclosure.Referring to FIG. 14, the second end surface 1434 of each of thetruncated tapered units 1430 is covered by the material layer 1420.Thereby, the second surface 1424 of the material layer 1420 can providea planar surface for the consequent bonding process.

However, the truncated tapered units may protrude from the materialafter their fabrication process. FIG. 15 illustrates an optical filmaccording to another embodiment of the present disclosure. Referring toFIG. 15, a planarization layer 1550 is fanned to cover the second endsurface 1534 of each of the truncated tapered units 1530 and a secondsurface 1524 of the material layer 1520, so as to provide a planarsurface for the consequent bonding process.

FIG. 16 illustrates an optical film according to another embodiment ofthe present disclosure. In this embodiment, a planarization layer 1650is formed to cover the carrying surface 1612 of the transparentsubstrate 1610 and the light absorbing layer 1640 before forming thematerial layer 1620 and the truncated tapered units 1630. By forming theplanarization layer 1650, a planar surface is provided for the followingfabrication process of the material layer 1620 and the truncated taperedunits 1630, and the formed first end surface 1632 of each of thetruncated tapered units 1630 is coplanar with a first surface 1622 ofthe material layer 1620.

FIG. 17 illustrates a display assembly according to another embodimentof the present disclosure. As shown in FIG. 17, the optical film 200 isbonded to the display unit 100 through an adhesion layer 1750. Thedisplay unit 100 of the present embodiment is for example an OLEDdisplay, which comprises a substrate 110, a first electrode 102, asecond electrode 106 in opposite to the first electrode 102, and a lightmodulation layer 104 interlaid between the first electrode 102 and thesecond electrode 106 for emitting the light L (as shown in FIG. 1). Thefirst electrode 102 is disposed nearby the material layer 220, and thesecond electrode 106 is away from the material layer 220. Herein, thelight modulation layer 104 may be a stacked structure of OLED whichcomprises an electron injection layer, an electron transport layer, anemission layer, a hole transport layer, and a hole injection layer. Thematerial of the adhesion layer 1750 may be acrylic resin or epoxy resin,and can be a pressure sensing adhesion or a filler adhesion. Thethickness of the adhesive layer 1750 may be less than or equal to 250μm. For example, the adhesive layer 1750 may be less than or equal to100 μm, or less than or equal to 50 μm.

FIG. 18 illustrates a display assembly according to another embodimentof the present disclosure. As shown in FIG. 18, the display assembly 10of FIG. 18 is similar with that of FIG. 17, except that: a barrier layer1850 is formed between the display unit 100 and the optical film 200, topreventing gas or moisture from entering the display unit 100 or theoptical film 200.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentdisclosure without departing from the scope or spirit of the disclosure.In view of the foregoing, it is intended that the present disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims and their equivalents.

1. An optical film, comprising: a transparent substrate, having acarrying surface; a material layer, disposed on the carrying surface ofthe transparent substrate; a plurality of truncated tapered units,disposed in the material layer, and each of the truncated tapered unitshaving a first end surface nearby the carrying surface and a second endsurface away from the carrying surface, wherein a ratio of an area ofthe first end surface and the area of the second end surface is largerthan or equal to 0.2 and is less than or equal to 0.6, and a reflectionsurface is formed between each of the truncated tapered units and thematerial layer to reflect a light which enters the truncated taperedunit through the second end surface, and the light reflected by thereflection surface is adapted to emerge from the truncated tapered unitthrough the first end surface; and a light absorbing layer, disposed onthe carrying surface and located between the transparent substrate andthe material layer, wherein the light absorbing layer has a plurality ofopenings, and a vertical projection of the openings on the carryingsurface overlaps a vertical projection of the first end surfaces of theplurality of truncated tapered units on the carrying surface.
 2. Theoptical film according to claim 1, further comprising a lining layerinterlaid between each of the truncated tapered units and the materiallayer, wherein a refractive index of the lining layer is higher than arefractive index of the material layer, and a total internal reflectionsurface is located on an interface between the lining layer and thematerial layer.
 3. The optical film according to claim 1, furthercomprising a lining layer interlaid between each of the truncatedtapered units and the material layer, wherein the lining layer is madeof metal, and the reflection surface is located on the interface betweenthe lining layer and each of the truncated tapered units.
 4. The opticalfilm according to claim 1, further comprising a reflective layer locatedbetween the light absorbing layer and the material layer, wherein thereflective layer and the light absorbing layer are substantially in asame pattern.
 5. A display assembly, comprising: a display unit having adisplay side; an optical film disposed on the display side of thedisplay unit, the optical film comprising: a transparent substrate,having a carrying surface facing the display unit; a material layer,disposed on the carrying surface of the transparent substrate; aplurality of truncated tapered units, disposed in the material layer,and each of the truncated tapered units having a first end surfacenearby the carrying surface and a second end surface away from thecarrying surface, wherein a ratio of an area of the first end surfaceand the area of the second end surface is larger than or equal to 0.2and is less than or equal to 0.6, and a reflection surface is formedbetween each of the truncated tapered units and the material layer toreflect a light which is emitted from the display unit and enters thetruncated tapered unit through the second end surface, and the lightreflected by the reflection surface is adapted to emerge from thetruncated tapered unit through the first end surface; and a lightabsorbing layer, disposed on the carrying surface and located betweenthe transparent substrate and the material layer, wherein the lightabsorbing layer has a plurality of openings, and a vertical projectionof the openings on the carrying surface overlaps a vertical projectionof the first end surfaces of the plurality of truncated tapered units onthe carrying surface.
 6. The display assembly according to claim 5,wherein a refractive index of each of the truncated tapered units ishigher than a refractive index of the material layer, and the reflectionsurface is a total internal reflection surface located on an interfacebetween each of the truncated tapered units and the material layer. 7.The display assembly according to claim 5, wherein the optical filmfurther comprises a lining layer interlaid between each of the truncatedtapered units and the material layer, a refractive index of the lininglayer is higher than a refractive index of the material layer, and atotal internal reflection surface is located on the interface betweenthe lining layer and the material layer.
 8. The display assemblyaccording to claim 5, wherein the optical film further comprises alining layer interlaid between each of the truncated tapered units andthe material layer, wherein the lining layer is made of metal, and thereflection surface is located on the interface between the lining layerand each of the truncated tapered units.
 9. The display assemblyaccording to claim 5, wherein the optical film further comprises areflective layer located between the light absorbing layer and thematerial layer, and the reflective layer and the light absorbing layerare substantially in the same pattern.
 10. The display assemblyaccording to claim 5, wherein the optical film further comprises abarrier layer covering the carrying surface and disposed between thetransparent substrate and the light absorbing layer.
 11. The displayassembly according to claim 5, wherein the optical film furthercomprises a barrier layer covering the carrying surface and the lightabsorbing layer.
 12. The display assembly according to claim 5, furthercomprises an adhesion layer disposed between the display unit and theoptical film.
 13. The display assembly according to claim 5, furthercomprises a barrier layer disposed between the display unit and theoptical film.
 14. The display assembly according to claim 5, wherein thesecond end surface of each of the truncated tapered units is covered bythe material layer.
 15. The display assembly according to claim 5,wherein the optical film further comprises a planarization layercovering the carrying surface and the light absorbing layer andproviding a planar surface for forming the material layer and thetruncated tapered units, wherein the first end surface of each of thetruncated tapered units is coplanar with a first surface of the materiallayer.
 16. The display assembly according to claim 5, wherein theoptical film further comprises a planarization layer covering the secondend surface of each of the truncated tapered units and a second surfaceof the material layer.
 17. The display assembly according to claim 5,wherein the display unit comprises a plurality of pixels, and an area ofeach pixel is greater than the area of the second end surface of each ofthe truncated tapered units.
 18. The display assembly according to claim5, wherein the display unit comprises: a first electrode, nearby thematerial layer; a second electrode, away from the material layer; and alight modulation layer interlaid between the first electrode and thesecond electrode for emitting the light.
 19. The display assemblyaccording to claim 18, wherein a distance between the display unit andthe optical film is less than or equal to 250 μm.
 20. The displayassembly according to claim 5, wherein the ratio of the area of thefirst end surface and the area of the second end surface is larger thanor equal to 0.25 and is less than or equal to 0.5.